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Reducing Aerodynamic Drag on Empty Open Cargo Vehicles

Friday, 24 July 2009

Open cargo bays are subdivided by means of simple partitions.

Some simple structural modifications
have been demonstrated to be effective in
reducing aerodynamic drag on vehicles
that have empty open cargo bays. The
modifications were originally intended to
be made in railroad coal cars because the
amounts of coal and the distances over
which they are transported by railroad in
the United States are so large that the
resulting reduction in drag could, potentially,
result in an annual saving of millions
of gallons of diesel fuel.

The basic idea is to break up the airflow
in a large open cargo bay by inserting
panels to divide the bay into a series
of smaller bays. In the case of a coal car,
this involves inserting a small number
(typically between two and four) of vertical
full-depth or partial-depth panels. For
example, as shown in Figure 1, two triangular
partial-depth vertical panels can be
conveniently attached to triangular
braces that are already integral parts of a
typical coal car.

In an experiment, measurements
of aerodynamic
drag on models of coal cars
were made in a wind tunnel.
The results of the measurements,
summarized in
Figure 2, clearly show the
drag-reducing effects of the
dividers; they also show that
the braces also contribute
small reductions of drag.

This work was done by
James C. Ross of Ames Research Center, Bruce L. Storms
of Aerospace Comput ing, Inc.,
and Dan Dzoan of Ohlone
College.

Inquiries concerning rights
for the commercial use of this
invention should be ad dressed
to the Ames Tech nology
Partnerships Division at
(650) 604-2954. Refer to
ARC-15422-1.

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